1. Field of the Invention
The present invention pertains to a tobacco product wrapping material comprising composite particles based on mineral particles, to a method for its production, and to its use in tobacco products. A main emphasis of the present application is on tobacco products with controlled burning properties.
2. Background of the Invention
Filter cigarettes usually consist of a cylindrical, round, or oval tobacco rod, which is wrapped by a cigarette paper; a similarly shaped filter plug, which is surrounded by a filter wrapping paper; and a tipping paper (base paper for the mouthpiece covering), which is usually glued to the entire filter wrapping paper and to part of the cigarette paper surrounding the tobacco rod and thus connects the filter plug to the tobacco rod. All these papers are to be designated in the following collectively as “tobacco product wrapping materials”.
Tobacco product wrapping materials usually contain fillers. Other additives can also be present to achieve special properties; such additives include wet-strength agents, substances which retard the combustion rate, and/or substances which accelerate the combustion rate.
Substances such as calcium carbonate, titanium dioxide, aluminum hydroxide, magnesium hydroxide, kaolin, calcined kaolin, talc and their mixtures are usually incorporated as fillers into the tobacco product wrapping materials, wherein, by suitable selection of the type and quantity of the fillers, both the optical properties and the burning properties can be controlled. Tobacco product wrapping materials which comprise no filler or only a small amount of filler can have a strong self-extinguishing effect on tobacco products, but tobacco product wrapping materials of this type do not have the desired optical properties such as a high degree of whiteness and a high degree of opacity.
With respect to tobacco product wrapping materials, furthermore, there are also limitations on the fillers which are allowed for use under the various applicable legal regulations. Calcium carbonate, according to the applicable regulations, can be used without restriction in all types of tobacco product wrapping materials. It is known, however, that certain fillers are disadvantageous with respect to the optical properties and burning properties. It is also known that tobacco product wrapping materials which comprise a large amount of filler and which also show controlled burning properties and also a desired self-extinguishing behavior when used in tobacco products require, in addition to calcium carbonate, a considerable proportion of other fillers or mixtures of other fillers as well as possibly additional substances which can be incorporated into the tobacco product wrapping materials such as those which, for example, retard the combustion rate.
It is also known in the relevant technical field that substances such as polymers, silicates, and polysaccharides and their derivatives in aqueous or non-aqueous solutions or suspensions can be applied in sufficient quantity and with a suitable geometric distribution to a tobacco product wrapping material, preferably a cigarette paper, for the purpose of influencing the burning properties of the tobacco product wrapping material.
In recent years, additional requirements on tobacco articles such as cigarettes have been enacted. Thus it has recently become a requirement that a tobacco article which continues to burn without self-extinguishing when smoked under normal conditions must self-extinguish when the tobacco article is placed on a combustible material, the purpose being to prevent the combustible material from catching fire. In other words, a controlled burning behavior is desired, in which the tobacco product burns down unimpeded along with the tobacco product wrapping material in freely accessible air, whereas, when resting on substrates, which may themselves be combustible, self-extinguishes shortly after contact with these substrates.
Japanese Patent Application No. 11-151082 A discloses a cigarette with controlled burning properties, in which a number of ring-shaped areas (combustion control areas) is arranged a certain distance apart in the longitudinal direction of the cigarette. These ring-shaped areas are in turn coated with a suspension comprising an inorganic filler such as chalk, clay, or titanium oxide in a cellulose polymer.
European Patent Application EP 1 321 048 A1 describes a tobacco article with controlled burning properties comprising a cigarette paper coated with a combustion-regulating agent, which is said to adjust the burning behavior of the tobacco article. As examples of suitable combustion-regulating agents, the document lists proteins such as gelatins, casein, albumin, and gluten; polysaccharide thickeners such as starch, xanthan (Echo Gum), locust bean gum, guar gum (Guarpack), gum tragacanth, “Tara” gum, tamarind seed polysaccharides (glyloid), gum karaya, gum arabic, pullulan, dextrin, cyclodextrin (Oligoseven), and gum ghatti; gelling polysaccharides such as carrageenan, curdlan, agar, furcellaran, pectin, “Jeram” gum, and “Kelco” gel; lipids such as lecithin; natural, high-molecular derivatives such as carboxymethylcellulose, methylcellulose, and propylene glycol alginate ester; processed starches such as starch phosphate; synthetic high-molecular compounds such as poly(sodium acrylate) and various high-molecular emulsifiers; inorganic ammonium salts such as ammonium chloride, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium bromide, and ammonium sulfate; inorganic hydroxides such as barium hydroxide, calcium hydroxide, and aluminum hydroxide; and flame retardants from inorganic salts such as sodium borate, boric acid, zinc chloride, magnesium chloride, calcium chloride, and sodium sulfate. EP 1 321 048 A1 describes that one or more of said combustion-regulating agents can be used.
CN 101747909 B discloses a flame-retarding additive comprising calcium carbonate and magnesium hydroxide, obtainable by preparing a magnesium sulfate solution, adding an alkaline calcium hydroxide suspension, adding a calcium chloride solution, and separating the precipitated material.
The disadvantage of the procedure described in this publication is that the method is time-intensive and complicated, comprising as it does a total of 10 steps, wherein step 9 alone takes 2-3 days. In addition, step 4 calls for an ultrasound treatment, which is very difficult to realize on an industrial scale.
The product obtainable in this way, furthermore, is not able to release significant amounts of water until the temperature exceeds 200 degrees Celsius (“° C.”). X-ray diffraction spectra of the product show that the product is a physical mixture of calcium carbonate and magnesium hydroxide.
In the U.S. Patent Application 2006/0162884 A1, mineral pigments are described, which contain a product obtained in situ by reaction of calcium carbonate with a weak or strong acid, gaseous carbon dioxide (“CO2”), and a certain salt. The salt to be used can be aluminum silicate; synthetic silica; calcium silicate; a silicate of a monovalent salt such as sodium silicate, potassium silicate, and/or lithium silicate; aluminum hydroxide; sodium aluminate; and/or potassium aluminate, wherein the content of monovalent silicate salts should be less than 0.1 weight percent (“wt. %”) based on the dry weight of the calcium carbonate. The mineral pigments obtainable in this way are said to have a pH, measured at 20° C., of greater than 7.5.
The BET surface area of the mineral pigment of this publication should preferably be in the range of 25-200 square meters per gram (“m2/g”).
In actual example 10 of this patent application, aluminum hydroxide powder and then sodium silicate are added to a suspension of natural calcium carbonate in water, and the resulting suspension is treated with phosphoric acid.
The addition of a metal salt to a calcium carbonate suspension, the salt having a solubility of greater than 9.0 milligrams per liter (“mg/L”) in the suspension measured at 20° C., is not, however, mentioned anywhere in the publication.
This application, furthermore, does not deal with the technical field of the present invention, namely, making available tobacco articles with controlled burning properties; on the contrary, it pertains to the making available of fillers for inkjet papers and has the particular goal of improving the printability of conventional coated or uncoated papers.
Finally, there are substances which cannot be used for the purposes of the present invention, namely, those in which calcium silicates are formed as the primary or secondary product, because silicates are not allowed in cigarette papers under the current regulations in this area.
The product obtainable in this way, furthermore, is not able to release significant amounts of water until the temperature exceeds 200° C. X-ray diffraction spectra of the product show that the product is a physical mixture of calcium carbonate and magnesium hydroxide.
WO 03/034845 A describes cigarettes with an increased self-extinguishing tendency, wherein the cigarette paper comprises ring-shaped zones, the air permeability of which is lowered by the presence of a polymer. The polymers in question are in particular polyvinyl acetate, partially hydrolyzed polyvinyl acetate, and polyvinyl alcohol.
EP 1 933 651 A1 describes a tobacco product wrapping material involving a base wrapping material, onto which, at least in separate zones, a composition is applied which comprises mechanically fragmented, chemically crosslinked polysaccharide with a particle size (weight-average particle size) of the dry polysaccharide product in the range of 1-1,000 micrometers (“μm”).
The fillers usually used in tobacco product wrapping materials thus suffer from limitations and disadvantages, especially because they do not make it possible to achieve effective control of the combustion behavior of the tobacco product wrapping material. It would be desirable, however, to have a tobacco product wrapping material comprising fillers in which the combustion behavior of the tobacco product wrapping material can be controlled effectively by the filler.
Against this background, better possibilities for reducing the flammability of combustible articles are to be presented. What is desired in particular are better solutions for controlling the burning properties and the self-extinguishing behavior of tobacco articles, above all better solutions for controlling the burning properties of tobacco articles in such a way that the tobacco articles burn under normal smoking conditions without self-extinguishing to the extent possible but do self-extinguish on contact with some other combustible material whose ignition is to be prevented as effectively as possible; that is, the tobacco product should burn down unhindered in the open air but self-extinguish on substrates which can themselves be combustible. It should be possible to realize the inventive solution in the simplest possible manner and at the lowest possible cost, and it should also be applicable universally to the extent possible.